1. Field of Invention
The invention relates to the manufacture of a composite profile based on a thermoplastic organic material reinforced with reinforcing fibres.
2. Discussion of the Background
For the sake of lightening a wide range of products, it is common practice to manufacture articles from plastic instead of more dense materials, the plastic being intrinsically reinforced, especially with fibrous reinforcements, in order to maintain the mechanical strength of the product.
It is known to use reinforcements comprising short fibres which are mixed directly with the plastic or are introduced in the form of composites such as granules comprising the reinforcements in a resin or plastic matrix. However, these short fibres do not make it possible to produce all the desired types of reinforcements, especially those for increasing the flexural strength of articles in one direction by a certain extent.
There are reinforcements based on continuous fibres in the form of cloths or fabrics more especially suitable for the manufacture of articles by moulding.
The incorporation of continuous reinforcing fibres into a profiled article, characterized by a long length compared with its other two dimensions, continues, however, to raise a few difficulties. This is because the technique of moulding is expensive and it appears to be desirable to develop other manufacturing solutions.
Patent Application FR 2,516,441 discloses a process for manufacturing thin profiles comprising unidirectional continuous glass fibres embedded in a thermoplastic resin.
The steps of the process for obtaining such profiles are as follows:                unwinding glass yarns from wound packages, in order to form a sheet of yarns;        separating the fibres of the yarns, in order to separate them because of the size with which they are coated;        dipping the sheet of glass fibres into an aqueous bath of a thermoplastic or else into a fluidized bed of powder of a thermoplastic;        heating the sheet in order to evaporate the water or to melt the powder, depending on the mode of dipping;        hot-shaping the resin-encapsulated sheet of fibres so as to produce the desired section.        
One drawback with this process is that it is necessary, in order for the fibres to be uniformly impregnated with the thermoplastic, to introduce the step of separating the fibres. This requires a specific device using several rollers, the number and arrangement of which, for ensuring the suitable winding angle of the sheet on these rollers, are determined by the degree to which the fibres stick together.
In addition, it is sometimes necessary, when the degree of sticking is too high, to provide heating means complementary to the rollers.
Consequently, there is a possibility that all the fibres are not completely separated from each other, in order subsequently to allow them to be encapsulated with the thermoplastic.
Moreover, the process uses for the impregnation a bath of a thermoplastic which has to be maintained at a constant level, the dispersion of which thermoplastic is constantly circulated in order to ensure as constant an impregnation as possible. Furthermore, the means employed in this bath are considerable and difficult to manage in a manufacturing line; these are elements such as a liquid delivery pump, a weir for establishing a constant level, a storage tank for the overflow, and a stirring device for ensuring that the contents of the bath are homogeneous, these elements having to be regularly cleaned.
In the variant of the impregnation device for the use of a fluidized bed, specific means are also necessary, especially a vibrating system mounted on springs, for metering the amount of powder taken away by the fibres.
Finally, the shaping device consists of a lower roller provided with a groove through which the sheet runs and of an upper roller serving to press the sheet. Thus, the various expected gauges of the profile entail the drawback of having to have available several rollers which have variously sized grooves, respectively.
Consequently, this process, being slow to carry out, proves to be expensive and of low performance.
This process is furthermore limited to the production of thin profiles and offers little freedom as regards the design of the cross section of the profile, especially if it is desired to adjust the amount of plastic in certain portions of the profiled cross section.
The object of the present invention is therefore to provide a process for manufacturing a composite profile based on a thermoplastic organic material reinforced by reinforcing fibres, which is easy and rapid to implement, as well as being economic from the industrial standpoint.
More particularly, the invention provides, by virtue of this process, a product in the form of a profile consisting, on the one hand, of at least one tape of continuous reinforcing yarns arranged so as to be approximately parallel and touching each other and consolidated by a first thermoplastic and, on the other hand, of at least one second plastic in intimate contact with the said tape(s).